The French prime minister has drawn criticism for suggesting that naked breasts are more representative of France than a headscarf, in the latest flare-up of the bitter political row over the burkini.

Manuel Valls, who clashed with France's education minister over his support for mayors who have banned full-body swimsuits from beaches, gave a rousing speech on Monday night in which he hailed the bare breasts of Marianne, a national symbol of the French Republic.

"Marianne has a naked breast because she is feeding the people! She is not veiled, because she is free! That is the republic!" he thundered at a government rally.